You are very wrong Richard as the Decafe green theme DOES have its own settings page
https://github.com/lazydaisy/moodle-theme_decaf_green/blob/master/settings.php
And as I mentioned to Mark, there is a section about the settings.php in the tutorial I had linked to.
The problem now that Mark will have, having Cloned Essential theme, are that the changes that Gareth makes in the future will need to be added again and again!
Thanks!
Mary